Field of the Invention
The present invention relates to optical fibers, in particular to a tool that facilitates cleaving of optical fibers to shorten their length and produce a flat end on the fiber.
Description of Related Art
There are many advantages to transmitting light energy via optical fiber waveguides and the use thereof is diverse. Single or multiple fiber waveguides may be used simply for transmitting visible light to a remote location. Complex communication systems may transmit multiple specific optical signals. These devices often require the coupling of fibers in end-to-end relationship with the coupling representing a source of light loss. The cleaved end should be smooth and defect-free. If the ends of the fiber are uneven, excessive light loss can result due to reflection and refraction of light at the cleaved end surface (e.g., a splice or juncture region). For the vast majority of fiber optic applications, it is important to cleave the fiber such that the end of the fiber is completely flat in preparation for coupling. When placing optical fibers in end-to-end relationship, to minimize light loss, it is desirable to have the end faces of the fibers be smooth and lie in a plane perpendicular, or at a specific angle, to the axis of the fibers. In short, the cleaved fiber end face needs to be a single plane that is mirror quality to optimize coupling between fibers in demountable connectors, permanent splices and photonic devices.
The relatively widespread and ever increasing utilization of optical fibers in communication systems, data processing and other signal transmission systems has created a demand for satisfactory and efficient means of inter-joining terminals. Currently most demountable fiber connectors are factory installed. For field installation of optical fibers, it is particularly desirable to develop a process that can be simply and reliably deployed to properly cleave the optical fibers so as to minimize light loss when the fibers are subsequently coupled.
An optical fiber can be cleaved to produce a flat end face by propagating crack growth in controlled fashion. In summary, optical fiber cleaving requires two principle steps: (a) scribing an annular groove around the circumference of the fiber, which serves as an initial shallow groove at the surface, and (b) applying a suitable tensile stress to cause a crack to grow and propagate across the optical fiber, beginning at the circumference and growing radially towards the center.
U.S. Patent Application Publication No. US2012/0000956 A1 (which had been commonly assigned to the assignee of the present invention, and fully incorporated by reference herein) discloses a process that can be simply and reliably deployed to properly cleave optical fibers to obtain smooth ends, so as to minimize light loss when the fibers are subsequently coupled. In accordance with the disclosure, axial tension is applied to an optical fiber that had been scored at the intended cleave location, wherein the axial tension is applied in a time-varying manner to maintain the stress intensity factor for crack on the fiber within an acceptable level to produce a stable crack growth from the circumference to towards the center at a reasonable rate to cleave the fiber. Careful control of the applied tension force with time acts to control the velocity of the propagating crack by maintaining substantially constant stress intensity factor. In one embodiment, the applied axial tension force is reduced with time and/or crack growth. As a result, the strain energy in the fiber material is released by formation of a single plane with an optical quality surface without requiring polishing. A substantially flat optical surface of enhanced optical quality is formed at the cleaved end of the optical fiber.
To facilitate the optical fiber cleaving process such as the process disclosed in U.S. Patent Application Publication No. US2012/0000956 A1, there is a need to develop an effective, convenient and reliable scribing tool to form an initial shallow circumferential groove at the surface, which could facilitate operations in field environment as well.